The current-voltage characteristics of microfabricated field emitters following inert gas ion bombardment have been investigated and correlated with changes in the electron-emission spatial distribution. The combination of glow discharge treatments in hydrogen and neon cause contaminant removal and mild emitter tip sputtering, leading to increases in the emitting area and significant improvements in the uniformity of the electron emission between tips in emitter arrays. The improved uniformity of the electron emission appears to be associated with a net smoothing of the emitter tip surfaces through the removal of field-enhancing protuberances by the inert gas ion bombardment.